Heart disease is the leading cause of death in the United States, according to the Centers for Disease Control and Prevention, killing more than 600,000 Americans annually.

“Heart disease is a broad term that encompasses many different problems,” said Navy Lt. Cmdr. Geoff Cole, staff cardiologist at Walter Reed National Military Medical Center in Bethesda, Maryland, and director of the anti-coagulation clinic.

Coronary artery disease, or CAD, is the most common heart disease. It’s caused by the buildup of plaque in the walls of the arteries supplying blood to the heart. Over time, the arteries narrow, blocking blood flow.

For many people, the first sign of having CAD is experiencing a heart attack. About 735,000 people in the United States have heart attacks annually, according to the CDC. About 30 percent of these occur in people who’ve already had one.

Risk factors for heart disease include gender, age, and family history. “Patients can’t do anything about these,” Cole said, “but other risk factors can be managed by adapting a healthy lifestyle.”

For example, diets high in refined foods, which have been manufactured and don’t have all their original nutrients, have been linked to increased risk of heart disease, as have some animal products. In general, red meat has more cholesterol and saturated fat than chicken, fish, and vegetable proteins. So Cole and other health experts recommend a diet rich in whole grains, fruits, nuts, vegetables, and legumes (a class of vegetable that includes beans, peas, and lentils).

Exercise is another important part of a healthy lifestyle. “Every time someone asks me how to prevent heart disease, I tell them to get moving,” Dye said. “Regular physical exercise is a significant part of maintaining a healthy heart.”

“And you don’t need to become a marathoner to reap the benefits of exercise,” Cole said. “Any activity that causes you to move is a good thing.” Cole recommends starting out slowly and then gradually increasing exercise over weeks to months to allow the body time to adapt and prevent injury.

Avoiding tobacco products is a third heart-healthy move. The chemicals in tobacco smoke can damage heart function as well as the structure and function of blood vessels, Dye said.

“Smokers are twice as likely to have heart attacks as people who’ve never smoked,” she said. “Every time you smoke, you increase your likelihood of having heart disease by 25 to 30 percent. And you’re harming those around you, because exposure to secondhand smoke also increases a person’s risk of heart disease.”

Dye said that unfortunately, she sees “too many young, active-duty service members in the cardiology clinic with early onset CAD. They’re exercising and eating right to meet physical fitness standards. But they smoke.”

Dye said kicking the cigarette habit can decrease the likelihood of CAD progressing. “So even if you’ve smoked your whole life, it’s time to stop.”

Cole said some people may feel overwhelmed by tackling diet, exercise, and quitting tobacco all at one time. “So make small changes,” he recommends, “because over time, they’ll become big changes.”

And the sooner, he said, the better. “Developing healthy habits when we’re young helps reduce our risk of developing heart disease as we age.”